package main 
import "fmt"
type User struct {
	username string 
	password string
	address Address			// User结构体嵌套了Address结构体
}

type Address struct {
	name string 
	phone string 
	city string
}

func main() {
	var user User 
	user.username = "admin"
	user.password = "123456"
	user.address = Address{name: "张三", phone: "123456789", city: "北京"}
	fmt.Printf("%#v\n", user)
}